Bacteriological and physico-chemical quality of drinking water sources in a rural community of Ethiopia

Background: Accesses to safe water is a universal need however, many of the world’s population lack access to adequate and safe water. Consumption of water contaminated causes health risk to the public and the situation is serous in rural areas. Objectives: To assess the bacteriological and physico-chemical quality of drinking water sources in a rural community of Ethiopia. Methods: Water samples were collected from tap, open springs, open dug wells and protected springs for bacteriological analysis of total coliforms and thermotolerant coliforms. The turbidity, pH and temperature were measured immediately after collection. Results : Most drinking water sources were found to have coliform counts above the recommended national and international guidelines and had high sanitary risk scores. There was a statistically significant difference among water sources with respect to TC and TTC (p < 0.05) and there was a statistically significant positive correlation between coliform counts and sanitary risk scores (p < 0.01). Most water sources didn’t satisfy the turbidity values recommended by WHO. Conclusion: The water sources were heavily contaminated which suggested poor protection and sanitation practice in the water sources. Source protection strategies as well as monitoring are recommend for this community.


Introduction
Accesses to safe water and sanitary means of excreta disposal are universal needs and indeed basic human rights; however, many of the world's population lack access to adequate and safe water 1 .Use of improved sanitation facilities is low especially in Sub-Saharan Africa and South Asia.Eight hundred eighty four million people in the world still do not get their drinking-water from improved sources; Sub-Saharan Africa accounts for over a third of that number.Fresh water has become a scarce commodity due to over exploitation and pollution.Increasing population and its necessities have led to the deterioration of surface and sub surface water 2 .
The greatest risk to public health from microbes in water is associated with consumption of drinking-water that is contaminated with human and animal excreta 3 .Human faeces can contain a variety of intestinal pathogens which cause diseases ranging from mild gastro-enteritis to the serious dysentery, cholera and typhoid.The most predominant waterborne disease, diarrhea, has an estimated annual incidence of 4.6 billion episodes and causes 2.2 million deaths every year 4 .Children are the main victims of diarrhea and other faecaloral disease, and also the most likely source of infection 5 .Total and fecal coliforms have been enumerated from various water sources 6 .The presence of fecal coliforms indicates the contamination of water with fecal material than may contain pathogenic organisms.These indicator bacterial were found to be more common in unprotected water sources than protected water sources 7 .
Ethiopia is characterized by lower water supply and sanitation coverage.It is estimated that 62.7% of the Ethiopian population relies on unimproved water sources and more than 80% of diseases in Ethiopia are attributed to poor access to clean water and sanitation 8 .The problem is more serious in rural area where the majorities of the people do not have access to potable water and therefore, depend on well, stream and river water for domestic use 1 .In the rural area where the study was conducted, there is insufficient amount of water during the dry season and hence, people are forced to fetch water from unimproved sources, travelling 2 km away from their homes.Even though certain households have pit latrines, they are poorly constructed and many people practice open defecation in places including those nearby the water sources..There is also intensive farming in the area and farmers introduce domestic animals in the field where drinking water are available.There is also no proper damping of animal wastes.Garbage and liquid waste are disposed in the surrounding field as well.These situations may lead to contamination of water sources.
Five hundred ninety one diarrheal cases were reported in the study area from July to December 2011.Among these, 305 were children (Personal Communication with District Health Officer).Despite these health hazards, no study has been done on the bacteriological and physico-chemical quality of waters in this area.Hence, the aim of this study was to analyze the bacteriological and physicochemical quality of drinking water from seven different water sources found in the rural areas of Northwest Ethiopia.

Description of the study area
The study was conducted in rural part of Northwest Ethiopia located 810 Km from the capital Addis Ababa.The area is located between 12 o 27´37½ -12 o 38´27½ North latitude and 36 o 57´30½ -37 o 10´06½ East longitude with an elevation range between 1860 -2240 m above sea level.

Water sampling and analysis
A cross sectional prospective study was conducted in rural areas of Northwest Ethiopia from November 2011 to February 2012 to assess the bacteriological and physic-chemical quality of water.A total of 53 water samples were collected from four sources namely: tap, protected dug well, open dug well and open spring.For bacteriological analysis, 250 ml of water sample was collected between 8:30 and 10:30 am with sterile glass bottle and transported to the laboratory in ice box.The number of total coliforms and thermotolerant coliforms was determined with the membrane filtration methods using Lauryl Sulfate-Broth (Blulux laboratories Ltd, India) 9 .For the determination of total coliforms and thermotolerant coliforms, incubation was carried out at 37 0 C and 44°C, respectively.Bacteriological analysis was done in triplicate within three hours of collection.
Temperature and pH were measured using WE30200 microprocessor; whereas, turbidity was measured using WE30140 potable turbidimeter (Singapore).Free residual chlorine, for 16 chlorinated water samples were determined using Wagtech comparator -Disc CD 109 with DPD number 1 chlorine tablets.All physico-chemical parameters were measured on site.Sanitary inspection of the water sources was also carried out using standard sanitary inspection formats and procedures 4 .

Data analysis
Data were entered, cleaned and analyzed using SPSS statistical package version 16.0.One way ANOVA was used to test if there are statistical differences in the tested parameters among the water sources.Spearman's correlation was used to check if there is correlation between bacteriological and physicochemical parameters.The results of bacteriological and physicochemical analyses were compared with national and WHO guidelines for drinking water.P-value < 0.05 was considered to indicate statistically significant association.Of the 16 treated water samples analyzed, 8 (50%) and 8 (50%) had residual free chlorine of 2-0.5 mg/ l and of 0-0.199 mg/l respectively (table 3).The concentration of residual free chlorine in most water samples were below the recommended limit of WHO (0.2-0.5 mg/l), which indicates the inefficiency of disinfection in the distribution system.Correlation analysis among bacteriological, physicochemical and level of risk parameters is shown in table 4.

Discussion
The results of the bacteriological quality of water sources in this study concord with the results of other studies conducted in Africa [10][11][12] .The presence of significant counts of coliform bacteria in the water sources is indicative of inadequacy of the depth of the wells or a breach of sanitary integrity of the wells 13 .The presence of coliforms in groundwater indicates that microorganisms from surface water have been able to reach the aquifer as supported by studies of Payment and Locas 14 .The presence of total coliforms in tap water after disinfection indicates inadequate treatment 3 .There was statistically significant difference among water sources with respect to TC and TTC (p < 0.05) where the average total coliform and thermotolerant counts were relatively higher in unprotected water sources compared to protected ones.Gwimbi 15 has reported a similar finding from a study done in Lesotho.
Sanitary inspection is used to identify causes of contamination and the risks of future contamination and overall assessment maintenance and operation of water sources 4,16 .A study conducted in Uganda, showed that total sanitary risk score showed a significant relationship with level of contamination 17 .In this study, there was statistically significant positive correlation between coliform counts and sanitary scores (r = 0. 817, p< 0.01) which is an indication for sanitary inspection's being a reliable tool for risk assessment of drinking water sources.A similar degree of correlation was reported from studies done in developing countries [17][18][19] .
Low pH values recorded in some open springs and dug wells may be due to saturation with carbon dioxide as indicated in other studies 20 .High temperature can favor the growth of organisms in water resources 21 .A similar study in Italy showed that the survival curves of Aeromones spp.decline rapidly at low temperature (5 0 C), whereas survival at temperatures greater than 20 0 C increases 22 .There was statistically significant difference in temperature among the water sources (p <0.05).Turbidity of water is an important parameter as it contributes to the aesthetics of water and leads to its acceptance or rejection for human consumption 3, 23 .
In areas where there is little risk of a waterborne outbreak, residual free chlorine of 0.2 to 0.5 mg/l at all points in the supply is recommended 23 .Therefore, when water leaves the treatment plant, residual free chlorine of about 1 mg/l is needed for health reasons and it is recommended that such level should be maintained at points of consumption 24 .The residual free chlorine recorded in this study is supported by a case study conducted in rural areas of South Africa 25 .General system failures, inefficiency in disinfection and poor maintenance are some of the factors that affect the quality of water in Ethiopia 23 .
The high density of indicator bacteria is therefore attributed to constructional defects, poor sanitation and existence of human activities and grazing near the water sources.The risk to heath matrix of the water sources showed from high to very high risks to cause disease.The study indicates that the rural people are under severe threat to water related diseases and health risks.The continuous consumption of such polluted water could pose serious health risks especially in children, elderly and immunocompromised individuals.

Conclusion
Water sources investigated were heavily contaminated.High total coliform and thermotolerant counts and high risk scores found in the water sources suggest poor source water protection and poor sanitation conditions and practices.These findings demonstrate the need to come up with source water protection strategies for rural communities where water treatment is not available.To this end, keeping the water sources safe by properly constructed fences, regular maintenances and supervisions of water sources and proper disposal of human and animal wastes are recommended.
open springs and open dug wells, 63.6% of protected dug wells and 30% of the tap water samples had total coliform counts above the national and WHO recommended limits.Similarly 72.8% of open springs, 63.7% of open dug wells and 36.4% of protected springs had thermotolerant coliform counts above the recommended national and international guidelines (table 1).open dug wells and open springs were at high risk category for total coliforms and the majority of open dug wells and 27% of protected dug wells and 20% tap water had high risk categories for total coliforms.Four water samples from each of protected dug wells and open dug wells had medium risk categories for total coliforms.Regarding thermotolerant colifroms, 6 (54.5%) and 4 (36.4%) of open springs and open dug wells respectively had high risk categories (table 2).

Table 1 :
Comparison of the bacteriological quality of four sources of water in rural Ethiopia

Table 2 :
Overall risk-to-health Classification of drinking water sources in rural Ethiopia

Table 3 :
Comparison of the physico-chemical quality of four sources of water with the WHO recommended values in rural Ethiopia

Table 4 :
Correlation among bacteriological, physico-chemical and level of risk parameters